Coupling for tubing



Jan. 2, 1945. J. R. DoRMAN COUPLING FOR TUBING Filed OCT.. 29, 1942Patented Jan. 2, 1945 UNITED STATES- PATENT oFFicE 2,366,444 coUPLmG Fon'runmc Jack B.. Dorman, Cincinnati, Ohio Y Application `October 29,19.42, Serial No. 463,785

1 Claim. (Cl. 285-86) This invention relates to a tubing and couplingconstruction and ls particularly directed to coupling means for tubingformed of a plastic material. More specifically, the invention relatesto the formation of the ends of conventional plastic tubing, theprovision of coupling elements for attaching these ends to the part tobe supplied or which is supplied, and the relationship of these parts sothat an effective and perfectly sealed coupling is formed. The presentimprovements are applied to standard and well-recognized plastic tubing.

Accordingly, it has been an object of the present inventor to providetubing having its ends formed in such manner as to cooperate with thecoupling elements to provide a sealing connection and a sufficientlyrigid connection without the application of any great-amount ofpressure. In fact, the coupling of this invention may be completedmerely by applying manual pressure.

In the development of the present invention, the inventor has recognizeda characteristic of this typey of tubing as well as a characteristic ofcertain types of compositions which may be used in the manufacture ofthe coupling ttings.

These parts, when clamped together, tend to grip more readily than hasbeen realized. Considerable friction occurs and this is believedto bedue to the compressibility andsoftness of the material. A remarkablytight connection can be procured with very little turning force.

It has been a further object of the present inventor to provide couplingelements associated with the formed ends of the tubing and in thiscombination to bring about a compressive action upon the formed end ofthe tubing. This action is assisted by the material of the tubing andthe connection is not easily broken by vibration. Due to the softness fthe materials, a tight seal is produced having the effectiveness 0f acoupling which includes a gasket.

It has been a further object of the present inventor to provide aformation at the end of the tubing and a coupling means wherein aspringing action is procured and wherein separate and not adjacentsurfaces of the same thickness of tubing material are gripped. Thus, aseal is produced at two points on separate portions of the tubingmaterial, and these portions are pressed toward each other wherein theycontinue to exert a spring action by tending to spring back to theirnormal uncoupled condition. The form of the coupling elements is suchthat a wedging Figure 3 is a view taken similar to Figure 2 but showingthe coupling fully tightened.

Figure 4 lis a fragmentary view showing a modied form of coupling.

Figure 5 is a sectional view of the coupling arrangement of Figure 4showing the coupling completed.

Figure 6 is a view showing a further modification of the coupling withthe parts separated.

surface when viewed from the exterior.

Figure 'l is a view showing the coupling of Figure 6 in coupled positionwith certain of the parts broken away and shown in section forillustrative purposes.

Referring generally to the drawing, a length of tubing is indicated atI0. This tubing is formed of a material which is plastic and preferablytransparent or translucent. The material ls highly flexible and has acertain amount ofr springiness. Its surface is not hard but rather maybe indented; ii; could hardly be called soft but at the same time itwill make veryclose contact with a surface engaged against it. It willadjust itself to any irregularities in the engaging surface and thus hasadmirable sealing qualities.

Thus, in the present instance, the inventor has specifically formed theends of this tubing so that they cooperate with coupling elements togive the maximum gripping and sealing action.

For this purpose, a cuif il is formed at the end of the tubing to beattached. Specifically, the end is turned outwardly and back upon itselfand presents a sort of beaded end for attachment purposes. The iiangeI2, constituting the cuff, is

rounded so that it presents an axially convex This provides for a,certain amount of flexing, yielding for. compression of the bead (noteparticularly Figure 3) when the coupling elements are clamped upon thebead. Further, this material has the structural characteristic that itmay be stretched a reasonable amount without splitting or rupturing.

In order to couple the end of the tubing thus formed to the partsupplying or being supplied.

or :ln any other environment. Where a connection is desired, twocoupling elements are desired. One oi' these, indicated at i3, isloosely slidably mounted on the tubing. This element isplaeed on thetubing prior to the formation of the cuil' or beading. It includes asleeve portion of substantial length including a bore Il through whichthe tube passes. Further, it includes an externally knurled grippingportion indicated at i5. Screw threads i6 are formed in an enlarged boreat the outer end of the element. The shoulder I1 between the plain boreil and the screw threads l is inclined or conical.

The other coupling element Il is also in the form of a sleeve includinga bore I9 throughout its length. It is provided with external screwthreads at each end, separated by a knurled gripping portion 2 l. Ateach end of the coupling element i8 is provided a plain extension 22,the end face of each plain extension being chamfered or conical. Theangles of these portions 23 correspond to the angle of the shoulder Il.

When the beaded end of the tubing is drawn upon the element i8, as thescrew threads Ii engage with screw threads 2li and the shoulder I1engages the cuii, the tapered end of the coupled element i8 enters theend of the tubing.

Thus, a spreading action ensues as shown in Figure 3. The materialstretches to permit this and an excellent sealing engagement is providedwithin the rounded internal surface 24 at the end of the tubing.Likewise, the engagement of the shoulder il with the cuil' tends toflatten or compress the cuil portion and the tension or sprnginess ofthe material continues thereafter to maintain a tight contact with theshoulder. In other words, a squeezing action is brought about on thebeaded end oi the tube that is upon the cuir and the adjacent endportion of the tube.

A composition material is used for the fitting elements and theIrlctional characteristics oi the surfaces of the coupling elements andthe tube material make it easy to obtain a tight seal and connectionwithout the use of a tool and merely by hand pressure. The cuir and theend portion of the tube engaged between the surfaces of the couplingelements are effective as a sealing gket.

In the modied form shown in Figures 4 and 5, the arrangement of thecoupling contact vsurfaces is slightly varied. f The iixed element 25 isengaged in a supporting wall 2i. The outer end of its bore 2l isscrew-threaded as at 2l. A plain bore portion 2l is provided beyond thescrew threads, that is. at the inner end o! the bore. The shoulderbetween the outer end of the bore the element 25, the cud or bead ispressed into the annular recess created by the inclined shoulder 3i andthe sealing action takes place within g the end of the tube against theshoulder 3l and against the outer surface of the cuil as at 35 throughthe inclined Vend face of the element 32. The same action of irictionalgrip and the compressibllity of the bead are present in this form.

In the :modification shown in Figures 6 and 7, the attached element 36provides an externally screw-threaded extension 3l. This elementincludes a plain end surface at right angles to the axes of the tubingand the coupling. The inner bore 38 oi' this coupling element and thatof the tubing ,are substantially of the same diameter. A coupling nut orsleeve 39, loosely mounted on the tubing, includes internal screwthreads for engagement on those of the element 3E. As in the form shownin Figures 1 to 3 inclusive, a tapered or conical shoulder '40 in thecoupling nui engages the outer surface of the cuir. Thus, in this form,the end o1' the tubing is abutted directly against the straight endsurface of the coupling 3B.

Having described my invention, I claim:

In a coupling, a length of tubing formed of plastic material, saidtubing having its end ared outwardly in a iiange turned back to form acurved cuil', the tubing having a dared opening to its bore, and a pairof coupllngelements, one having an internally conical end adapted toengage the culi and the other oi' said coupling elements having a.groove, one wall of which forms a tapered seating surface adapted toengage within the iiared opening of the tubing, said last named taperedseating surface being substantially parallel to said conical end, thebore of the tiret-named coupling element being adapted to closely engagethe exterior of the tubing for forc-v ing the culi into saidgroove,whereby the cuil' and the material of the tubing adjacent thereto aregripped together between the conical surface and the tapered seating ofthe othervcoupling element, the plastic material of-the cui! beingyieldable and pliable for producing a sealed connection.

JACK R. DORMAN.

